Method of metal-drawing.



H. G. CARLSQN. METHOD 0F METAL DRAWING.

APPLICATION FILED AUG.2, 1915.

Patented 00L. 3, 1916.

2 SHEETS-SHEET .1.

H. G. CARLSON.

' METHOD 0F METAL DRAWING.

APPLICATION FILED/waz. 1915. l

' Patented 0t.'3,191 6 2 SHEETS-SHEET 2 HJALMAR G. CARLSON,y F WORCESTER, MASSACHUSTTS, SSIGNOR 10 RQKWOD SPRINKLER COMPANY 0F MASSACHUSETTS, A CORPORATIGN 0F MASSACHUSETTS. l

ivni'rnon or METAL-DRAWING.

Lacasse.,

` To all whom t mag/ concern: f

Be it known that I, HJALMAR- G. CARL- soN, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented 'a new and useful Method of Metal-Drawing, of which the following is a specification.

This invention relates to a method of producing a hollow article of sheet metal which I will call ashell and which may be used for many purposes in accordance with its particular size andv shape. A characteristic feature of 'the article, however, .is that it varies in thickness from itsclosed end to its open end, being thicker at the open'end. Also it may have in addition an integral enlargement at its open en'd formed by the thickening process instead of being doubled over or creased so that it has no internal seam.

The principal objects of the invention are y to provide a method of producing an article such as above described, and particularly to provide means whereby by a simple drawing operation the open end ot a yshell-shaped ai'ticle can be thickened and the closed end reduced in thickness at each drawing operation so that by a series of successive-drawing operations of this character' an article can be produced which will have a materially thickened open end; also to provide in cooperation in'these series of' drawing operations other steps by which. the closed end .is reduced in thickness and the article is finally shaped up to the desired definite shape.

Reference is to be had to the accompanying drawings, in which,

Figure is a transverse sectional view ef a die showing a. plunger in position for performing the first operation; Eig. 2 is .a similar view showing the second operationg. Fig. 3 is a sectional view of a itlerent form of die and a plunger showing the operation of reducing the thickness oit' the end or' the blank; Figs. a, and 6 are views similar to Figs. l yand 2 showing three yotherspeciic steps of the same character those illustrated in Figs. l and 2; Fig. v7 is a similar View showing the irst step oi' the methodI of bringing the blank up to a definite shape after the preliminary op-l erations shown in the tir-st six figures; Fig. is a similar view showing the completion o''this step, and Fig. 9 is aI side View of the completed article.

Specification of Letters Patent.

rlhis invention is designed for the producv. i I A i Patented Oct. 3, 1916. Application led August 2, '1315. Serial No. 43,084.

tion of a 'shell having a cylindrical surface inside, provided with a closed end and anv open end, and having the metal thickerfatv its open end than at its closed end and growing so progressively from one end to ther other. Heretofore, these articles have-been formed by machine operations and haveA been made in a comparatively expensive manner. I have 'discovered that such ank article can be made with equal accuracy by simple drawing operations, thus reducing itsexpense by a very greatV percentage and I have also discovered a principle of metal drawing which can be'used in this method to advantage, namely thatwhen a blankis y drawn through a smaller die by means of a plunger smaller inldiameter thanv the internal diameter of the blank at all stages of the said drawing step, thedrawing operation will have the eiiect of drawing out the blank as would be expected, but in addition thereto, has the'fturther eii'ect of thickening the open edg .of the blank. This` thickening effect, progresses substantially uniformly from the closed tothe open end,vespecially after the blank has been subjected to a number 'of these operations. Furthermore, I iind that an enlarged shoulder at theopen end of the blank can also be formed practically byv this operation, so that the complete article is homogeneous throughoutv and'has no line of cleavage formed by folding the metal on itself, as would be the case if it were formed by the usual sheet metal -work-` ing operations.

Referring nowto the drawings-,-the first stepin the process is to take a flat blank and place it on top of av die 10 which has a perforation or opening 11 of a shape corre'- sponding with the shape of the desired 'article, in this case circular. rlhis opening also is smaller than the diameter of the flat hlank which. is to be operated upon.A This iat blank is 'forced intothe rdie and preferably through` it by a plunger 12 which iscylindrical in form. The blank a vwhich is being operated upon is thus forced into the shape shown in this figure, but it is to be observed; that the diameter of the plunger is` slightly'- 'lessthan the diameter of the die opening the opening ll, it will not` touchtheinner i10- l.circular walls'of the blank at its closed end.

. The result of this operation is to draw the y larger than in i to touchthe blank at all points,

-plunger 12. If it does,

space is filled, consequently the blank metal of the' blank so as to elongate it and to' fold. inthe outer edge ofthe blank so be the same tendency to thicken but it could not 'The cup-shaped blank a having4v been proand its edge is thickened still further.

duced in accordance with the arrangement shown in Fig. 1., it is then placed in a second die 2O and forced through it by a plunger 22. The relation between this die an plunger is the same as that between the first named die and plunger and the effect is the same, that'is a blank aisproduced having a furtherl elongationand smaller dametr t that this thickening exfrom the opento the is found in practice tendsv substantially -'closed end of the blank so that `the blank 'y and before that shown in may be considered as having a conicalinnel surface, although it is not aperfect cone. The blankis thereafter subjected to a vsuccession of these operations in a series of dies and plungers all having the same relation to each other, as hasbeen described, and a series of blanks a2, a3, and a* is obtained, each one smaller and longer than the one from which it is made and thicker at its open edge. The dies and plungers operating-on ,the blanks'a?, a3, and a* are designated respectivelyl 30,40, 50 and 32, an intermediate point in this process, preferably after the operation shown vin Fig. 2, Fig. 4, theclosed end ofthe blank is flattened and thinned by subjecting the blank to pressure between a flat bottomed die 23 and a plunger also having a flatbot'tom. This plunger may be ifdesired made of exactly size as'the plunger -22 the same shape land and may in lfact be the same one as indicated. If desired, the

die 23 can be located just below the die 20 and receive the plunger and blank as soon 'as the latter is freed from the die 20 by passof which it is produced and that ing entirely through it.

It will be understood that the number of operations above described will depend upon the article being ,produced and the Ametal is notlimited to any particular number of such operations.

After the blank,-has,been brought to the condition shown at L4 in which it isof sublinner surface,

42 and 52. At

this method stantially the diameter and length desired, the rough, thickened openend is squared off by any desired means, and then it is put through the finishing operations, as shown in Figs. 7 and 8. ln Fig. 7 it is shown as being forced into a die 53, which instead of having a cylindrical passage, therethrough, is provided with a. cavity having three cy.- lindrical portions 5a, 55 and 56 of different sizes. The blank is forced into this die by a plunger 57 which is cylindrical throughout and has an enlarged part 58 with a square shoulder. The 'die 53 is shown as consisting of two parts but that is not essential. .'lhe result .of this operation is to produce-a blank a5 and especially to form itsinterior into a true cylindrical form throughout most of -its length and bring the` variation on the outside, preparatory Vto making it conical in formon the exterior. At the top theinside is. not shaped definitely, but it is gaged to length by the square shoulder and somewhat thickened at the top preparatory to forming a projecting shoulder.

The next operation shown in Fig. 8 consists in forcing the blank into a die 60 having a conical surface G1 and an enlarged cylindrical surface 62. Thisis done by means of a plunger 63 of cylindrical form throughout and having an enlarged head 64 provided with a flat lower surface. Theresult of. this operation-is to finish the shell a so as to give it a complete true-cylindrical a trueconical outer surface, and an enlarged cylindrical shoulder at the top having asquare end. Upon being removed from this die and plunger, the shell is ready for any machining 'operations such shoulderV of the shell af.

From this description it will beseen that a shell is secured which is thinner at its closed end than` anywhere else and progressively grows thicker ltoward its open end and yet it is cylindrical inside and a true conical shape outside. Furthermore, it is provided with an enlarged shoulder for receiving the screw-threads a7 formed gradually by the die pressing and drawing operations, and finally shaped up by the finishing operations without folding any metal on itself and thus without providing a seam within it. In this way an article is secured having a maximum strength and of a maxim'um degree of perfection throughout, and yet the method of producing it is so extremely expeditious that when a large number of articles are done ina most inexpensive lmanner and without waste of stock except such as is involved in cutting out the first fiat blank 4from a sheet of metal.

Although I have illustrated and described a certain number and sequence of steps and to be produced it can be shown the method as appliedto the produc- -tion of a; specified article, I am aware of the fact that the invention is not limited in these respects and therefore l do not wish to be s0 limited except as set forth in the claims. y l

Having described the invention what I claim is l. The method of drawing metal which comprises Aforcing'a blank through a die by means of a plunger, leaving a space between the die and plunger around the latter slightly greater than the original thickness of the metal, whereby the metal for a distance from its edge will buckle upon itself and thicken but will be shaped and drawn out between metal out to a thickness greater than its original thickness at that region, whereby the inside diameter of the blank will'be left greater at the closed en d than at the open end.v

3. The method of drawing metal which comprises forcing a blank through a die by means ol' a plunger, leaving a space between the die and plunger around the latter yslightly greater than the original thickness of the metal, whereby the metal for a distance from its open edge will buckle upon itself and thicken but will be shapcdvand drawn out between the die and plunger, and thereafter forcing the formed blank through a second die by means of a plunger for reducing the diameter of the blank and leaving a space between the die :and plunger slightly greater than the maximum thickness ot the first named formed blank, whereby the buckling, thickening and drawing operation will be repeated. Y

4. The method nl drawing out and upsetting a flat lil-ank which consists in forcing the llat blank through a. die by means of a )lune'er to cause the metal. alone the edffe l r l *9 comprises forcing a blank through a die by of the blank to` buckle on itself, causing it to thicken at the edge and to assume a cylindrical form in Contact with the surface of the die and at the same time causing the metal near said edge of the blank to re-` main in contact with and be shaped by the plunger so as to draw the thickened'metal out to a greater thickness than it originally had at that point and leaving a space between the end of the plunger and blank to allow the cross section of the blank at the end to remain less than at the edge.

5. Thev method of drawing metal which comprises forcing a blank through a die by` means ot a plunger, leaving a space between the die and plunger around the latter slightly greater than the original thickness of the metal, whereby the metal for a distance from its edge will buckle upon itself and thicken but will be shaped and drawn out between the die and plunger, whereby the blank is given a uniform outside shape from end to end. but its inside diameter at the closed end is greater than itis at its open end, squaring ofi" the openf` end and then simultaneously drawing out 'tthe closed end of the blank, shaping 'itl to afuniform inside diameter nearly toits open end ,and gaging it for length.

6. The method of drawing metal which means ot a plunger, leaving a space between the die and plunger around the latter slightly greater than the original thickness of the metal, whereby the metal for `a distance from its'cdge will buckle upon itself and thicken '50 but will be shaped and drawn out between the die and plunger, whereby the blank is given a uniform outside shape from end to end, but its inside diameter at the closed end is greater than it is at its open end, squaring oit the open end and then simul- `laneously drawing out the'closed end of the blank, shaping it to a uniform inside diameter nearly to its open end and further enlarging its open end to iorm an integral seamless shoulder.

. .ln testimony whereof I have hereunto set my hand, in the presence utf-two subscribing witnesses. i

- HJALMAR G. CARLSQN.

i Vltnesses: i

l ll. CLAYTON KnNnALL,

D. NV. Omvrsnnn. 

